I would suspect you fan switch is not the problem but it is possible. Normally this is caused by a defective blower motor resistor pack. Inspect that before replacing the fan switch.
Typically this is a failure of the headlight switch assembly. See the question about how to replace the headlight switch in a 1991 Cherokee for the answer of how to accomplish.
You switch the carborator with the ac and then rewire the inside to the dashboard
How do you replace the safety neutral switch on a 1995 Jeep Cherokee 5-speed transmission and Where is the safety neutral switch located?
The 1993 Jeep grand Cherokee brake light switch simply plugs in and out. The brake light switch is located beneath the dashboard on the drivers side of the engine compartment.
Check the brake light switch located on the brake pedal lever. If there is power to the switch but nothing coming out replace it. Did you check the bulbs? Is there power to the rear sockets?
No This is not easy. It is easier to replace the signal light switch assembly
The brake light switch, on a Dodge neon, can be found under the dashboard just below the steering column. The brake light switch just unplugs. Unplug the switch and replace with a new one.
The headlight switch to the left of the steering wheel on the front of the dash acts as the dimmer. You spin the switch right or left depending on the intensity of the light you prefer.
On my 96 Cherokee Country there is a button on the underside of the switch that releases the knob and shaft and the shaft just pushes back in until it catches.
http://www.youtube.com/watch?v=reonxApWkVU
The neutral safety switch and backup light switch are one in the same. You have to replace it. It is located on the transmission where the shifter connects to it.
There is a lock ring on the inside of the dash where the switch connects. You need to remove this lock ring to remove the switch from the dash.